1. Field of the Invention
The present invention is directed to an agricultural combine rotary crop-processing unit having a rotor disposed within a rotor housing and in particular to such a combine in which the rotor housing is frusto-conical while the rotor is generally cylindrical. The housing is arranged relative to the rotor such that the gap between the rotor and the bottom of the housing is generally constant along the length of the housing while the gap between the top of the rotor and the top of the housing gradually increases in the crop flow direction.
2. Description of the Related Art
Rotary combines having a rotary crop-processing unit are well known. Examples are shown in U.S. Pat. Nos. 5,445,563 and 5,688,170 assigned to the assignee of the present application. These two patents both disclose rotary crop processing units having two or more sections. The relationship between the rotor axis and the housing axis varies from one section to the other. In both of these patents, the rotor axis becomes increasingly offset from the housing axis in the crop flow direction from the housing inlet to the housing outlet. This is accomplished by abrupt transitions in the housing structure between sections where the housing shape changes. As the housing shape changes, the housing axis steps upward relative to the rotor axis and the gap between the rotor and the top of the housing increases at each step in the housing.
In a co-pending patent application, also commonly assigned, Ser. No. 378,773, filed Aug. 20, 1999, the rotor and the housing are both generally cylindrical and are arranged such that their axes are nearly concentric at the inlet and diverge in the crop flow direction with the housing axis diverging upward from the rotor axis in the to produce a gradual increase in the gap between the rotor and the top of the housing in the crop flow direction.
The present invention provides yet another structure for a crop-processing unit to provide an increasing gap between the top of the rotor and the housing in the crop flow direction. The housing of the present invention is frusto-conical in shape when viewed in a vertical section along the housing axis with the housing arranged relative to the rotor such that the top of the housing diverges from the rotor axis in the crop flow direction. This results in the gap between the rotor and the top of the housing gradually increasing in the crop flow direction. The increasing gap between the rotor and the housing enables the crop mat to expand as it passes through the crop-processing unit which aids in separation of the grain from the straw.
The housing radial section can be either circular or oval. With a circular radial section, the housing can also be mounted in the supporting structure of the combine to rotate about the housing axis as well as having the rotor rotate about the rotor axis.